The manipulation of nanoscale objects is one of the great outstanding challenges for the fabrication of nanosensors and nanodevices that will drive future technologies. Precise control over single molecules, in particular, will impact a number of areas of intense research interest. For example, it will enable the planned (as opposed to purely heuristic) assembly of molecular-scale devices, revolutionize single molecule characterization techniques where short dwell times in the observation volume are the main obstacle, and lead to new tools for biomedical diagnosis with single molecule sensitivity. Any such manipulation must be preceded by an efficient, reliable method for confining (trapping) an object on demand.